Saturday, March 31, 2012

What Crab Neurobiology Tells Us: Going Beyond the Mean to the Individual

As we all learned in Kindergarten, all
individuals are different. But as Eve Marder pointed out today at CNS
2012, we sometimes forget this important and simple lesson,
especially when relying on only the mean to analyze data. Her work
on crustaceans is revealing that big differences in individual
neuronal processes can still produce similar outcomes, enabling
populations to survive while maintaining diversity.

Marder, a neurobiologist, is the
recipient of this year's George A. Miller Prize, which recognizes
scientists in various disciplines who have “the potential to
revolutionize cognitive neuroscience,” said George Mangun of the
University of California, Davis, in his introduction of Marder for
today's address at the annual meeting in Chicago. Marder's work on small neuronal networks in
invertebrates has great significance to human brains and possibly all
animal brains.

Since 1980, Marder and her research
team at Brandeis University have been analyzing nervous systems from
the stomachs of crustaceans. The so-called “stomatogastric”
nervous system acts as a functional circuit with a well-defined
output pattern. The researchers have tested how variations in the
parameters of the circuit can still produce a stable set of outcomes
even with environmental changes.

In one study, for example, Marder's
team tested how crabs' stomatogastric nervous systems react to
temperature changes. At low temperatures, they found that all
networks compensated and kept a stable output. But once the crabs
became stressed at high temperatures, they all crashed in different
ways that varied depending on the individual neuronal circuitry. Only
when they were stressed, she said, did their diversity become
apparent.

Altogether, Marder said her work is
demonstrating that there are multiple “good-enough solutions” to
circuit performance so that populations can survive under diverse
environmental conditions. It is important, she says to remember that
“not every individual in a population is well-represented by the
mean,” and she hopes to further explore how individual structural
differences in neuronal systems affect animals' functions.